As filed with the Securities and Exchange Commission on July 1, 1999.

                                                 Registration No. 333-76271
- --------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                         POST-EFFECTIVE AMENDMENT NO. 1
                                       ON
                                    FORM S-8
                                       TO
                                    FORM S-4
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

                              BANCWEST CORPORATION
             (Exact name of registrant as specified in its charter)


            Delaware                                     99-0156159
- -------------------------------------        ----------------------------------
 (State or other jurisdiction of                      (I.R.S. Employer
 incorporation or organization)                      Identification No.)

        999 Bishop Street
        Honolulu, Hawaii                                    96813
- -------------------------------------        ----------------------------------
      (Address of Principal                              (Zip Code)
       Executive Offices)

                   SIERRA TAHOE BANCORP 1996 STOCK OPTION PLAN

                   SIERRA TAHOE BANCORP 1998 STOCK OPTION PLAN

       CALIFORNIA COMMUNITY BANCSHARES CORPORATION 1993 STOCK OPTION PLAN

             CONTINENTAL PACIFIC BANK 1990 AMENDED STOCK OPTION PLAN

     SIERRAWEST BANCORP DIRECTORS DEFERRED COMPENSATION AND STOCK AWARD PLAN

                            (Full title of the plan)

                                                            Copy to:
        WILLIAM E. ATWATER, ESQ.
Senior Vice President and General Counsel             RODNEY R. PECK, ESQ.
          BancWest Corporation                    Pillsbury Madison & Sutro LLP
            999 Bishop Street                             P.O. Box 7880
            Honolulu, Hawaii                         San Francisco, CA 94120
             (808) 525-7000                              (415) 983-1000
     ------------------------------              ------------------------------
      (Name, address and telephone
      number, including area code,
          of agent for service)


CALCULATION OF REGISTRATION FEE - ------------------------------------------------------------------------------------------------------------------------------ Title of Amount Proposed Maximum Proposed Amount of Securities To To Be Offering Price Maximum Aggregate Registration Be Registered Registered per Share Offering Price Fee - ------------------------------------------------------------------------------------------------------------------------------ Sierra Tahoe Bancorp 1996 Stock Option Plan Common Stock 138,535 (2) (1) (1) (1) Sierra Tahoe Bancorp 1988 Stock Option Plan Common Stock 123,185 (2) (1) (1) (1) California Community Bancshares Corporation 1993 Stock Option Plan Common Stock 21,156 (2) (1) (1) (1) Continental Pacific Bank 1990 Amended Stock Option Plan Common Stock 4,629 (2) (1) (1) (1) SierraWest Bancorp Directors Deferred Compensation and Stock Award Plan Common Stock 10,000 (2) $38.34 (3) $383,400 (3) $106.59 (3) (1) Not applicable. All filing fees payable in connection with the registration of these securities were paid with the initial filing with the Securities and Exchange Commission of the Registration Statement on Form S-4 (Registration No. 333-27671), filed on April 14, 1999, being amended by this post-effective amendment. (2) There is also being registered hereunder such additional undetermined number of shares of the Registrant's Common Stock as may be required as a result of stock dividends, stock splits, or other similar adjustments of the Registrant's outstanding Common Stock. (3) Estimated in accordance with Rule 457(h) and Rule 457(c) of the Securities Act of 1933 solely for the purpose of calculating the registration fee as follows: $383,400 or 10,000 shares of Common Stock based on a price of $38.34 per share, the average of the high and low trading prices of the Common Stock of the Registrant on the consolidated reporting system on June 25, 1999. INTRODUCTORY STATEMENT NOT FORMING PART OF REGISTRATION STATEMENT BancWest Corporation ("Registrant") hereby amends its Registration Statement on Form S-4 (Registration No. 333-76271) filed on April 14, 1999, by filing this Post-Effective Amendment No. 1 on Form S-8 relating to an aggregate of 297,505 shares of Common Stock of the Registrant (the "Shares"). The Shares to be registered hereunder are issuable by the Registrant pursuant to options or obligations to issue shares assumed by the Registrant pursuant to an Amended and Restated Agreement and Plan of Merger, dated as of February 25, 1999 (the "Agreement"), among the Registrant, Bank of the West and SierraWest Bancorp. Such options or obligations were originally granted under (i) the Sierra Tahoe Bancorp 1996 Stock Option Plan, (ii) the Sierra Tahoe Bancorp 1998 Stock Option Plan, (iii) the California Community Bancshares Corporation 1993 Stock Option Plan, as amended and restated March 19, 1996, (iv) the Continental Pacific Bank 1990 Amended Stock Option Plan, and (v) the SierraWest Bancorp Directors Deferred Compensation and Stock Award Plan (the "Directors Plan"), each as amended to date (collectively, the "Plans"). Pursuant to the Agreement, SierraWest Bancorp will be merged (the "Merger") with and into Bank of the West, a wholly-owned subsidiary of the Registrant. Options to purchase SierraWest Bancorp Common Stock granted under the Plans and outstanding immediately prior to the completion of the Merger shall become options to purchase the Common Stock of the Registrant at the effective time of the Merger and any obligations to issue shares of the Common Stock of SierraWest Bancorp to any directors shall become obligations to issue shares of the Common Stock of the Registrant. -2-

Pursuant to its Registration Statement on Form S-4, Registrant registered 4,624,004 shares of its Common Stock, representing the number of shares of its Common Stock issuable in connection with the Agreement in exchange for SierraWest Bancorp Common Stock, assuming exercise of all then outstanding options to purchase SierraWest Bancorp Common Stock. The designation of this Post-Effective Amendment No. 1 as Registration No. 333-76271 denotes that this Post-Effective Amendment No. 1 relates only to an aggregate of 297,505 shares of Common Stock of the Registrant issuable to any director under the Directors Plan or issuable upon conversion of options granted under the Plans listed above and that this is the first post-effective amendment to the Form S-4. PART I ------ INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS ---------------------------------------------------- The document(s) containing the information specified in Part I of Form S-8 will be provided to participants as specified by Rule 428(b)(1) of the Securities Act of 1933, as amended (the "Securities Act"). These documents and the documents incorporated herein by reference pursuant to Item 3 of Part II of this Registration Statement, taken together, constitute a prospectus that meets the requirements of Section 10(a) of the Securities Act (the "Prospectus"). PART II ------- INFORMATION REQUIRED IN THE REGISTRATION STATEMENT -------------------------------------------------- Item 3. Incorporation of Certain Documents by Reference. - ------- ------------------------------------------------ The following documents filed by Registrant with the Securities and Exchange Commission are incorporated by reference in this Registration Statement: (1) The Registrant's Annual Report on Form 10-K for the fiscal year ended December 31, 1998; (2) The Registrant's Quarterly Report on Form 10-Q for the quarter ending March 31, 1999; (3) All other reports of the Registrant pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (the "Exchange Act") since December 31, 1998; (4) The description of the Registrant's Common Stock contained in the Registration Statement (and past and future amendments thereto, including without limitation the Registrant's Form 8-A filed on October 30, 1998) for such stock filed under Section 12 of the Exchange Act. In addition, all documents subsequently filed by the Registrant pursuant to Section 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this registration statement and to be a part hereof from the date of filing of such documents. Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement. -3-

Item 4. Description of Securities. - ------- -------------------------- Not applicable. Item 5. Interests of Named Experts and Counsel. - ------- --------------------------------------- Not applicable. Item 6. Indemnification of Directors and Officers. - ------- ------------------------------------------ The Registrant is incorporated under the laws of Delaware. Section 145 of the Delaware General Corporation Law provides for the indemnification of officers and directors of a Delaware corporation under certain circumstances against expenses, judgments, and the like in connection with an action, suit, or proceeding. Article X of the Registrant's Amended and Restated Bylaws provides for indemnification of directors and officers under certain circumstances. The Registrant has purchased a standard liability policy, which, subject to any limitations set forth in the policy, indemnifies the Registrant's directors and officers for damages that they become legally obligated to pay as a result of any negligent act, error, or omission committed while serving in their official capacity. Banque Nationale de Paris, the holder of 100% of the Class A Common Stock of the Registrant, has agreed to indemnify the persons who serve as Class A Directors of the Registrant (who are elected by the holder of the Class A Common Stock) under certain circumstances against expenses, judgments, and the like in connection with an action, suit, or proceeding by reason of the fact that the person is or was a Class A Directors. Item 7. Exemptions from Registration Claimed. - ------- ------------------------------------- Not applicable. Item 8. Exhibits. - ------ --------- 5.1 Opinion of Pillsbury Madison & Sutro LLP. 23.1 Consent of PricewaterhouseCoopers LLP, Independent Auditors. 23.2 Consent of Pillsbury Madison & Sutro LLP (included in Exhibit 5.1). 24.1-24.20 Powers of Attorney Item 9. Undertakings. - ------- ------------- (a) The undersigned Registrant hereby undertakes: (1) To file, during any period in which offers or sales are being made, a post-effective amendment to this Registration Statement: (i) To include any prospectus required by section 10(a)(3) of the Securities Act of 1933; (ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be -4-

reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; (iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement; Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the registration statement is on Form S-3 or Form S-8, and the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed by the Registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement. (2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. (3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering. (b) The undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the Registrant's annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. (c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue. -5-

SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Honolulu, State of Hawaii, on June 30, 1999. BANCWEST CORPORATION By /s/ HOWARD H. KARR -------------------------------------- Name: Howard H. Karr Title: Executive Vice President and Chief Financial Officer Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed on June 30, 1999, by or on the behalf of the following persons in the capacities indicated with the registrant. Signature Title --------- ----- * Chairman, Chief Executive Officer and - ----------------------------------- Walter A. Dods, Jr. Director (Principal Executive Officer) /s/ HOWARD H. KARR Executive Vice President and Chief - ----------------------------------- Financial Officer (Principal Financial Howard H. Karr and Accounting Officer) * Director - ---------------------------------- Jacques Ardant * Director - ---------------------------------- John W. A. Buyers * Director - ---------------------------------- Dr. Julia Ann Frohlich * Director - ---------------------------------- Robert A. Fuhrman * Director - ---------------------------------- Paul Mullin Ganley * Director - ---------------------------------- David M. Haig -6-

Signature Title --------- ----- * Director - ---------------------------------- John A. Hoag * Director - ---------------------------------- Bert T. Kobayashi, Jr. * Director - ---------------------------------- Michel Larrouilh * Director - ---------------------------------- Vivien Levy-Garboua * Director - ---------------------------------- Yves Martrenchar * Director - ---------------------------------- Dr. Fujio Matsuda * Director - ---------------------------------- Don J. McGrath * Director - ---------------------------------- Rodney R. Peck * Director - ---------------------------------- Joel Sibrac * Director - ---------------------------------- John K. Tsui * Director - ---------------------------------- Jacques Henri Wahl * Director - ---------------------------------- Fred C. Weyand * Director - ---------------------------------- Robert C. Wo * By Power of Attorney -7-

Signature Title --------- ----- /s/ HOWARD H. KARR Attorney-in-Fact - ------------------------------------ Howard H. Karr -8-

INDEX TO EXHIBITS - ----------------- Exhibit - ------- Number Exhibit - ----- ------- 5.1 Opinion of Pillsbury Madison & Sutro LLP. 23.1 Consent of PricewaterhouseCoopers LLP, Independent Auditors. 23.2 Consent of Pillsbury Madison & Sutro LLP (included in Exhibit 5.1). 24.1-24.20 Powers of Attorney -9-





                                                                    EXHIBIT 5.1

                          PILLSBURY MADISON & SUTRO LLP
                              235 Montgomery Street
                             San Francisco, CA 94104
                               Tel: (415) 983-1000


                                  July 1, 1999




BancWest Corporation
999 Bishop Street
Honolulu, HI 96813


         Re:      Registration Statement on Form S-8


Ladies and Gentlemen:

     We refer to the Registration Statement on Form S-8 (the "Registration
Statement") to be filed by BancWest Corporation, a Delaware corporation (the
"Registrant"), with the Securities and Exchange Commission under the Securities
Act of 1933, as amended, relating to 297,505 shares of Common Stock of the
Registrant (the "Shares") issuable upon the exercise of options originally
granted by SierraWest Bancorp ("SierraWest") or granted pursuant to the
SierraWest Bancorp Directors Deferred Compensation and Stock Award Plan (the
"Directors Plan"). The Shares to be registered hereunder are issuable by the
Registrant pursuant to obligations or options assumed by the Registrant pursuant
to an Amended and Restated Agreement and Plan of Merger, dated as of February
25, 1999, among the Registrant, Bank of the West and SierraWest Bancorp. Such
options and shares were originally granted under (i) the Sierra Tahoe Bancorp
1996 Stock Option Plan, (ii) the Sierra Tahoe Bancorp 1998 Stock Option Plan,
(iii) the California Community Bancshares Corporation 1993 Stock Option Plan, as
amended and restated March 19, 1996, (iv) the Continental Pacific Bank 1990
Amended Stock Option Plan, and (v) the Directors Plan, each as amended to date
(collectively, the "Plans"). We advise you that, in our opinion, such Shares,
when granted pursuant to the Directors Plan or when issued and sold in
accordance with the Plans and, where applicable, with option agreements duly
authorized under the Plans and in accordance with the Registration Statement,
will be legally issued, fully paid and nonassessable.

     We hereby consent to the filing of this opinion with the Securities and
Exchange Commission as Exhibit 5.1 to the Registration Statement.

     This opinion letter is rendered as of the date first written above and
we disclaim any obligation to advise you of facts, circumstances, events or
developments which hereafter may be brought to our attention and which may
alter, affect or modify the opinion expressed herein. Our opinion is expressly
limited to the matters set forth above and we render no opinion, whether by
implication or otherwise, as to any other matters relating to the Registrant,
the Plans or the Shares.

                                Very truly yours,


                                /s/ PILLSBURY MADISON & SUTRO LLP




                                                                   EXHIBIT 23.3



                       CONSENT OF INDEPENDENT ACCOUNTANTS


We hereby consent to the incorporation by reference in this Registration
Statement on Form S-8 (to be filed on or about July 1, 1999) of our report
dated January 21, 1999 relating to the consolidated financial statements,
which appears in the 1998 Annual Report to Shareholders of BancWest
Corporation, which is incorporated by reference in BancWest Corporation's
Annual Report on Form 10-K for the year ended December 31, 1998.

                                /s/  PRICEWATERHOUSECOOPERS LLP

Honolulu, Hawaii
July 1, 1999




                                                                   EXHIBIT 24.1


                                POWER OF ATTORNEY


     KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer
or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as
set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD
H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California,
and each of them, his true and lawful attorney and agent, to do any and all acts
and all things and to execute any and all instruments which said attorney and
agent may deem necessary or desirable to enable the Issuer to comply with the
Securities Act of 1933, as amended (the "Act"), and any rules, regulations and
requirements of the Securities and Exchange Commission thereunder, in connection
with the registration under the Act of such number of shares of common stock of
the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the
Issuer's obligations arising under Section 2.6 of the Amended and Restated
Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer,
Bank of the West and SierraWest Bancorp including, without limitation, the power
and authority to sign the name of the undersigned in the capacity indicated
below to the Registration Statement on Form S-8 to be filed with the Securities
and Exchange Commission with respect to such Shares, to any and all amendments
or supplements to such Registration Statement, whether such amendments or
supplements are filed before or after the effective date of such Registration
Statement, to any related Registration Statement filed pursuant to Rule 462
under the Act, and to any and all instruments or documents filed as part of or
in connection with such Registration Statement or any and all amendments
thereto, whether such amendments are filed before or after the effective date of
such Registration Statement; and the undersigned hereby ratifies and confirms
all that such attorney and agent shall do or cause to be done by virtue hereof.

     Date:  June 10, 1999.

                                    /s/  WALTER A. DODS, JR.
                                    ------------------------------------
                                    Walter A. Dods, Jr.
                                    Chairman, Chief Executive Officer and
                                    Director (Principal Executive Officer)


EXHIBIT 24.2 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 23, 1999. /s/ JACQUES ARDANT --------------------------------- Jacques Ardant Director

EXHIBIT 24.3 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ JOHN W. A. BUYERS ------------------------------------- John W. A. Buyers Director

EXHIBIT 24.4 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 15, 1999. /s/ DR. JULIA ANN FROHLICH --------------------------------------- Dr.Julia Ann Frohlich Director

EXHIBIT 24.5 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 12, 1999. /s/ ROBERT A. FUHRMAN ------------------------------------ Robert A. Fuhrman Director

EXHIBIT 24.6 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 9, 1999. /s/ PAUL MULLIN GANLEY ---------------------------------- Paul Mullin Ganley Director

EXHIBIT 24.7 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ DAVID M. HAIG ---------------------------------- David M. Haig Director

EXHIBIT 24.8 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ JOHN A. HOAG ----------------------------------- John A. Hoag Director

EXHIBIT 24.9 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 10, 1999. /s/ BERT T. KOBAYASHI, JR. ------------------------------------- Bert T. Kobayashi, Jr. Director

EXHIBIT 24.10 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 15, 1999. /s/ MICHEL LARROUILH ----------------------------------- Michel Larrouilh Director

EXHIBIT 24.11 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 23, 1999. /s/ VIVIEN LEVY-GARBOUA ------------------------------------ Vivien Levy-Garboua Director

EXHIBIT 24.12 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ YVES MARTRENCHAR ----------------------------------- Yves Martrenchar Director

EXHIBIT 24.13 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ DR. FUJIO MATSUDA --------------------------------- Dr. Fujio Matsuda Director

EXHIBIT 24.14 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ DON J. MCGRATH ---------------------------------- Don J. McGrath Director

EXHIBIT 24.15 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ RODNEY R. PECK ----------------------------------- Rodney R. Peck Director

EXHIBIT 24.16 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 11, 1999. /s/ JOEL SIBRAC ---------------------------------- Joel Sibrac Director

EXHIBIT 24.17 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 10, 1999. /s/ JOHN K. TSUI --------------------------------------- John K. Tsui Director

EXHIBIT 24.18 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 14, 1999. /s/ JACQUES HENRI WAHL ------------------------------------- Jacques Henri Wahl Director

EXHIBIT 24.19 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ FRED C. WEYAND ------------------------------------------ Fred C. Weyand Director

EXHIBIT 24.20 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that the undersigned, being an officer or director, or both, of BANCWEST CORPORATION (the "Issuer"), in his capacity as set forth below, hereby constitutes and appoints WALTER A. DODS, JR. AND HOWARD H. KARR, of Honolulu, Hawaii, and DON J. MCGRATH, of San Francisco, California, and each of them, his true and lawful attorney and agent, to do any and all acts and all things and to execute any and all instruments which said attorney and agent may deem necessary or desirable to enable the Issuer to comply with the Securities Act of 1933, as amended (the "Act"), and any rules, regulations and requirements of the Securities and Exchange Commission thereunder, in connection with the registration under the Act of such number of shares of common stock of the Issuer (the "Shares") as are necessary at the Effective Time to satisfy the Issuer's obligations arising under Section 2.6 of the Amended and Restated Agreement and Plan of Merger dated as of February 25, 1999 among the Issuer, Bank of the West and SierraWest Bancorp including, without limitation, the power and authority to sign the name of the undersigned in the capacity indicated below to the Registration Statement on Form S-8 to be filed with the Securities and Exchange Commission with respect to such Shares, to any and all amendments or supplements to such Registration Statement, whether such amendments or supplements are filed before or after the effective date of such Registration Statement, to any related Registration Statement filed pursuant to Rule 462 under the Act, and to any and all instruments or documents filed as part of or in connection with such Registration Statement or any and all amendments thereto, whether such amendments are filed before or after the effective date of such Registration Statement; and the undersigned hereby ratifies and confirms all that such attorney and agent shall do or cause to be done by virtue hereof. Date: June 17, 1999. /s/ ROBERT C. WO ------------------------------------- Robert C. Wo Director